org.orekit.propagation.semianalytical.dsst.forces

Interface DSSTForceModel

All Known Implementing Classes:

AbstractGaussianContribution, DSSTAtmosphericDrag, DSSTCentralBody, DSSTSolarRadiationPressure, DSSTThirdBody

public interface DSSTForceModel

This interface represents a force modifying spacecraft motion for a DSSTPropagator.

Objects implementing this interface are intended to be added to a DSST propagator before the propagation is started.

The propagator will call at the very beginning of a propagation the initialize(AuxiliaryElements, boolean) method allowing preliminary computation such as truncation if needed.

Then the propagator will call at each step:

1. the initializeStep(AuxiliaryElements) method. The force model instance will extract all the elements needed before computing the mean element rates.
2. the getMeanElementRate(SpacecraftState) method. The force model instance will extract all the state data needed to compute the mean element rates that contribute to the mean state derivative.

The propagator will call the getShortPeriodicVariations(AbsoluteDate, double[]) method at the end of the propagation in order to compute the short periodic variations to be added to the mean elements to get the final state.

Author:

Romain Di Constanzo, Pascal Parraud

Method Summary

Methods

Modifier and Type	Method and Description
void	computeShortPeriodicsCoefficients(SpacecraftState state) Compute the coefficients used for short periodic variations.
EventDetector[]	getEventsDetectors() Get the discrete events related to the model.
double[]	getMeanElementRate(SpacecraftState state) Computes the mean equinoctial elements rates dai / dt.
double[]	getShortPeriodicVariations(AbsoluteDate date, double[] meanElements) Computes the short periodic variations.
void	initialize(AuxiliaryElements aux, boolean meanOnly) Performs initialization prior to propagation for the current force model.
void	initializeStep(AuxiliaryElements aux) Performs initialization at each integration step for the current force model.
void	registerAttitudeProvider(AttitudeProvider provider) Register an attitude provider.
void	resetShortPeriodicsCoefficients() Reset the coefficients used for short periodic variations.

Method Detail

initialize

void initialize(AuxiliaryElements aux,
              boolean meanOnly)
                throws OrekitException

Performs initialization prior to propagation for the current force model.

This method aims at being called at the very beginning of a propagation.

Parameters:

aux - auxiliary elements related to the current orbit

meanOnly - only mean elements are used during the propagation

Throws:

OrekitException - if some specific error occurs

initializeStep

void initializeStep(AuxiliaryElements aux)
                    throws OrekitException

Performs initialization at each integration step for the current force model.

This method aims at being called before mean elements rates computation.

Parameters:

aux - auxiliary elements related to the current orbit

Throws:

OrekitException - if some specific error occurs

getMeanElementRate

double[] getMeanElementRate(SpacecraftState state)
                            throws OrekitException

Computes the mean equinoctial elements rates da_i / dt.

Parameters:

state - current state information: date, kinematics, attitude

Returns:

the mean element rates dai/dt

Throws:

OrekitException - if some specific error occurs

getShortPeriodicVariations

double[] getShortPeriodicVariations(AbsoluteDate date,
                                  double[] meanElements)
                                    throws OrekitException

Computes the short periodic variations.

Parameters:

date - current date

meanElements - mean elements at current date

Returns:

the short periodic variations

Throws:

OrekitException - if some specific error occurs

getEventsDetectors

EventDetector[] getEventsDetectors()

Get the discrete events related to the model.

Returns:

array of events detectors or null if the model is not related to any discrete events

registerAttitudeProvider

void registerAttitudeProvider(AttitudeProvider provider)

Register an attitude provider.

Register an attitude provider that can be used by the force model.

Parameters:

provider - the AttitudeProvider

computeShortPeriodicsCoefficients

void computeShortPeriodicsCoefficients(SpacecraftState state)
                                       throws OrekitException

Compute the coefficients used for short periodic variations.

Parameters:

state - current state information: date, kinematics, attitude

Throws:

OrekitException - if some specific error occurs

resetShortPeriodicsCoefficients

void resetShortPeriodicsCoefficients()

Reset the coefficients used for short periodic variations.

This method is aimed to reset short periodics coefficients. It is called when one goes from a interpolation step to the next one.